The invention relates to an excavator, particularly a shovel excavator arrangement comprising:
a superstructure which can be swivelled on an undercarriage about a first vertical axis,
a boom swivel block pivotally supported at the superstructure so that it can be swivelled about a second vertical axis,
a jib held at the boom swivel block, and
a swivelling device connecting the boom swivel block and superstructure, said swivelling device comprising a hydraulic cylinder connected with the swivel block by means of a guide rod.
From the German Patent Document DE-A 27 57 968, a mobile shovel excavator is known which has a boom swivel block which can be swivelled by way of a hydraulic cylinder by approximately 90.degree. from a position in a transverse plane of the vehicle to a position in a longitudinal plane of the vehicle when the revolving superstructure is aligned in the driving direction. The jib, which is pivotally connected to the boom swivel block and has the shovel, can be swivelled on the swivel block by way of a torque motor into a position alongside the revolving superstructure. In the case of this pivotal connection of the boom swivel block, additional devices are required, such as the torque motor, in order to swivel the jib into a transport position.
From the German Patent Document DE-A 34 25 838, another shovel excavator is known which has a swivel device that is connected with the boom swivel block and comprises a hydraulic cylinder connected with the swivel block by means of a guide rod. Because of the construction of the swivel device, the jib of this shovel excavator cannot be placed in a transport position alongside the revolving superstructure so that, as a result of the poor visibility, a road operation at a relatively high speed does not seem possible.
It is an object of the invention to provide a shovel excavator whose jib, by way of a structurally simple swivel device, ensures a relatively large swivel path and permits a driving in road traffic with good visibility at a relatively high speed.
According to the invention, this object is achieved by providing an arrangement wherein the boom swivel block with the jib can be rotated by means of a driven crank mechanism from a forward working end position extending diagonally with respect to the longitudinal center axis of the excavator superstructure about the second vertical axis of rotation, into a swivelled-back transport position with respect to the driving direction in which the jib is arranged parallel to the longitudinal center axis and laterally of the superstructure.
Principal advantages achieved by the invention are that the jib can be displaced from its forward working position to a swivelled-back rearward transport position by means of a swivel device constructed as a crank mechanism, in which case the jib is to be arranged alongside the revolving superstructure and approximately in parallel to the longitudinal center axis of the excavator, and thus the prerequisite exists for a fast driving on the road because the visibility is improved.
The crank mechanism for the boom, which consists essentially of an angle lever and the connecting control rod, has a small size so that only little space is required for its housing. The parts of the crank mechanism, because of their kinematic points, also require only little clearance for their swivel movements.
The crank mechanism is designed in such a manner that in the transport position, that is when the jib is disposed alongside the revolving superstructure, there is a low torque, and the forces to be supported are relatively low because significant loads no longer occur in this position. In the working positions, for example, in an intermediate working position when the jib is swivelled out transversely with respect to the driving direction (FIG. 3), and in a forward working end position (FIG. 1), approximately the same torque is reached. A higher torque exists between these working positions because of the changing lever lengths of the crank mechanism, but the forces to be supported in the axes of rotation remain essentially equally large in all working positions.
Other objects, advantages and novel features of the present invention will become apparent from the following detailed description of the invention when considered in conjunction with the accompanying drawings.